Project-1: Powertrain for aircraft in runways
Project 1 : Powertrain for aircraft in runways
Q.1 Search and list out the total weight of various types of aircrafts.
Ans=>
This is a list of aircraft sorted by maximum takeoff weight.
Airplanes
MTOW = Maximum take-off weight, MLW = Maximum landing weight, TOR = Take-off run , LR = Landing run
Maximum Takeoff Weight:
The maximum weight limits for an aircraft to begin its takeo roll is called the max takeoff weight.
Maximum Landing Weight:
The maximum landing weight is, as you might imagine, the maximum aircraft weight limit approved for an aircraft to land. Landing above this weight can cause structural damage.
Helicopters
Convertiplanes
Q.2 Is there any difference between ground speed and air speed ?
Ans=>
Ground speed
Ground speed is the horizontal speed of an aircraft relative to the ground. An aircraft heading vertically would have a ground speed of zero. Information displayed to passengers through the entertainment system of airlines aircraft often gives the aircraft ground speed rather than airspeed.
Ground speed can be determined by the vector sum of the aircraft's true airspeed and the current wind speed and direction; a headwind subtracts from the ground speed, while a tailwind adds to it. Winds at other angles to the heading will have components of either headwind or tailwind as well as a crosswind component.
For a reference point picked on the ground, the aircraft moves relative to the reference point at the ground speed. Ground speed is also a vector quantity so a comparison of the ground speed to the wind speed must be done according to rules for vector comparisons.
Wind Speed
For a reference point picked on the ground, the air moves relative to the reference point at the wind speed. Notice that the wind speed is a vector quantity and has both a magnitude and a direction. Direction is important. A 20 mph wind from the west is different from a 20 mph wind from the east. The wind has components in all three primary directions (north-south, east-west, and up-down). In this figure, we are considering only velocities along the aircraft's flight path. A positive velocity is defined to be in the direction of the aircraft's motion. We are neglecting cross winds, which occur perpendicular to the flight path but parallel to the ground, and updrafts and downdrafts, which occur perpendicular to the ground.
Airspeed
The important quantity in the generation of lift is the relative velocity between the object and the air, which is called the airspeed. Airspeed cannot be directly measured from a ground position, but must be computed from the ground speed and the wind speed. Airspeed is the vector difference between the ground speed and the wind speed.
Airspeed = Ground Speed - Wind Speed
On a perfectly still day, the airspeed is equal to the ground speed. But if the wind is blowing in the same direction that the aircraft is moving, the airspeed will be less than the ground speed.
Q.3 Why is it not recommended to use aircraft engine power to move it on ground at Airport?
Ans=>
Major disadvantage while use aircraft engine power to move it on ground at Airport are :
1. Fuel Consumption.
2. Wear and tear on the engine.
3. Unnecessary jet blast and noise.
⦁ Too Much Fuel is Wasted While Taxiing :
Taxiing, sometimes called “taxying”, refers to an aircraft’s movement while on the ground, under its own power. This term excludes the accelerating run along a runway before takeoff and the decelerating run immediately upon landing.
By using jet engines as an aircraft’s primary thrust for taxiing, airlines are expending huge amounts of jet fuel while still on the ground, which could be much better used for flying. With the Cost of Fuel being their single biggest expense, many airlines plan to adopt electric taxiing to save fuel and reduce environmental impacts.
⦁ Jet Efflux Hazard is defined as hazards associated with the blast force generated behind a jet engine. The hazard exists whenever a jet engine is running but is increased and extends over a greater area and at greater distance behind the engine, at high engine power settings when taxiing, before and during take-off, and during engine maintenance activity.
⦁ Operationally, jet efflux can be hazardous in three ways:
⦁ 1. In the ramp environment where it can damage other aircraft, blow over ground equipment (baggage carts, aircraft steps, vehicles, etc.), cause structural damage to buildings, or injure or kill passengers, crew and ground personnel who may be in the vicinity.
⦁ 2. On taxiways where other aircraft (and especially jet engines) may be damaged by Foreign Object Debris (FOD) and smaller or light aircraft blown over or subjected to loss of directional control.
⦁ 3. On surface manoeuvring areas that are either damaged or not designed to withstand the efflux from engines running at high power.
⦁ The Risk to Operational Safety:
The risks which may arise from engine ground running relate to the potential for loss of control of the aircraft by those persons occupying the pilot seats in the flight deck. Effectively a loss of control - especially during high power engine running. Damage can occur to the aircraft itself, other aircraft nearby or to airside structures. In addition, there is a risk of injury to ground support personnel who may be in relatively close proximity to the aircraft.
Because of these some drawbacks it is not recommended to use engine power to move on ground at airport.
Q.4 How an aircraft is pushed to runway when its ready to ready to take off?
Ans=>
How Planes Work
Airplanes fly when the movement of air across their wings creates an upward force on the wings (and thus the rest of the plane) that is greater than the force of gravity pulling the plane toward the earth. The physics behind this phenomenon was first described by Daniel Bernoulli, an 18th century Swiss mathematician and scientist who studied the movement of fluids. Bernoulli discovered that the pressure exerted by a moving fluid is inversely proportional to the speed of the fluid. In other words, fluid pressure decreases as fluid speed increases, and vice versa.
The Phases of Flight
Push-Back and Taxi-Out
Aircraft are not always moved with tugs (the small vehicle you refer to). Much of the time, they operate under their own power.
Airliners are generally pushed back from the gate using a tug, as that's the simplest and most efficient method. They then taxi to the runway (and all the way up to the gate, after landing) using their own engines to provide thrust. This is true of both jets and propeller aircraft.
Some work is being done on self-contained electric-powered ground propulsion; one major player in this area is a company called WheelTug. They use high-torque motors and the aircraft APU to allow the aircraft to move itself without starting its engines or requiring a tug to be connected and disconnected.
This first phase of flight, after all doors have been secured, involves the movement of the aircraft away from the terminal jetway and along taxiways to a runway. A motorized vehicle called a tug sometimes is used to push the aircraft back from its gate.
At some airports, certain aircraft are permitted to power back. This means that following engine start at the gate, the thrust reversers are used to literally back the aircraft away from the gate.
The aircraft then moves under its own power along the taxiways. Since aircraft are designed primarily for flight, and are not ground vehicles, they are taxied at very low speeds. Push-back occurs only when the pilot has clearance to do so from Air Trafic Control, which monitors all aircraft movements during taxi.
Q.5 Learn about take off power, tyre design, rolling resistance , tyre pressure , brake forces and landing.
Ans=>
Take off power=>
Power Requirement to Keep a Jet Aircraft in the Air
The total energy of an aircraft flying in the atmosphere can be calculated using equation,
E = ½ m v2+ mgh
However, the engines mounted onto the wings of the plane are required to provide additional energy per time, power, in order to keep the aircraft flying at a constant altitude and speed. This extra power needed to overcome the drag acting on the airplane and is calculated using
P = (dh/dt) m g
where (dh/dt) is the decent speed required to keep the plane's speed constant if the engines fail.
Takeoff and Climb :
When ready for takeoff, and cleared by Air Trafic Control to proceed, the pilot or first officer of an aircraft releases the brakes and advances the throttle to increase engine power to accelerate down the runway.
Once aligned on the runway, steering the aircraft is normally accomplished by using foot pedals that manipulate the nose wheel until the speed is sufficient enough that wind rushing by the rudder on the aircraft tail makes nose wheel steering unnecessary.
As the aircraft gains speed, air passes faster and faster over its wings and lift is created. Instruments onboard the aircraft display this airspeed, which equals not only the speed of the plane relative to the ground, but also the speed of any wind that may be blowing toward the aircraft (aircraft normally take off headed into the wind). When the airspeed reaches a certain predetermined point known as rotation speed, the pilot manipulates panels on the tail of the aircraft to rotate the nose of the plane upward. This creates even stronger lift and the plane leaves the ground.
Rotation speed, abbreviated VR, is one of three important airspeed settings calculated before every flight.
The others are V1 - the speed beyond which a safe stop on a runway is no longer possible; and V2 - the minimum speed needed to keep a plane flying should an engine fail after the aircraft surpasses V1. Some of the factors affecting VR and V2 are the weight of the aircraft, the air temperature and the altitude of the airport. The heavier the aircraft, the more lift, and thus speed is needed to get it off the ground. Aircraft also need to go faster to y on a hot day than on a cool day. Hot air is less dense than cool air and less density produces less lift for the same speed.
Similarly, the higher the altitude, the less dense the air. Aircraft need more speed to leave the ground at a place like Denver than at a place like New York, with all other factors such as weight being equal. Some of these factors also are important in calculating V1, although the key factor is the length of the runway that is being used.
Most large jets leave the ground at about 160 miles per hour and initially climb at an angle in excess of 15 degrees. The angle of a plane's wings to the air owing around them is extremely important to maintaining lift. If the so-called angle of attack is too severe, the ow of air around the wings becomes disrupted and the plane loses lift.
To make an aircraft more aerodynamically effcient, the wheels on which an aircraft rolls when it is on the ground are retracted into a cavity in the belly of the plane after it is airborne. There is less drag (wind resistance), and an aircraft can fly faster when its landing gear is retracted.
Tyre design :=>
When it comes to safety tyres are one of the most important components of aircraft. They help to absorb the shock of landing and provide cushioning. It also provides the necessary traction for braking and stopping of an aircraft.
An aircraft tyre is designed to withstand extremely heavy loads while landing, take off, taxing and parking. The number of wheels required for aircraft increases with the weight of the aircraft, as the weight of the aeroplane needs to be distributed more evenly.
A Boeing 737NG & 737MAX uses 6 wheels, Boeing 787 uses 10 wheels, Boeing 777 uses 14 wheels and Airbus A380 uses 22 wheels. Aircraft tyres work under extreme conditions, carrying up to 340 tons and accelerating at over 250 km/hour at takeoff, in addition to enduring varied environmental stress when in flight and taxiing.
Design and Construction of Aircraft tyre
Carcass plies are used to form the tire. They are sometimes called casing plies. An aircraft tyre is constructed for the purpose it serves.
1. They support the weight of an aircraft while it is on the ground.
2. It also provides the necessary traction for braking and stopping of an aeroplane.
3. Tyre also helps to absorb the shock of landing and provide cushioning the roughness of takeoff, roll-out, and taxi operations.
Unlike an automobile or truck tyre, it does not have to carry a load for a long period of continuous operation. However, an aircraft tyre absorbs the high impact loads of landing and also it’s operating at high speeds for a short time when required.
Some technical aspects of the tyre :
Retreading – Retreading is methods of restoring a worn tyre by renewing the tread area or by renewing the tread area plus one or both sidewalls. Repairs are included in the tyre retreading process.
Load Rating – Load rating is the maximum permissible load at a specified inflation pressure.
Ply Rating – Ply Rating is used to identify the maximum recommended load rating and inflation pressure for a specified tyre. It is an index of tyre strength.
Speed Rating – The speed rating is the maximum takeoff speed to which the tyre has been tested.
Skid Depth – Skid depth is the distance between the tread surface and the deepest groove as measured in the mould.
Aircraft tyres must have an approved speed and load rating and have sufficient clearance when retracted through landing gear to allow for tyre growth. Tyre growth is the increase in the size of the tyre due to centrifugal forces at high speed.
Aircraft tyres may be Tube-type or Tubeless
Tubeless tyres are more advantageous over tube-type. There is no longer the use of tube-type tyre in recent aviation. Nowadays all airliners are using tubeless tyres. Tubeless that are meant to be used without a tube has the word TUBELESS on the sidewall of the tyre.
Aircraft tyres may be Radial or Bias
Almost all airliners are using Radial tyre. Bias is an older design, and it’s mainly used for road vehicles. Radial tyres have the word RADIAL on the sidewall. Radial tires are more expensive than bias-ply tyres. Radial tires are in demand because of their lower life cycle cost and long term value.
Radial tyre construction :
Radial tires are the most modern design of aircraft tyres. It is a design that is similar to that of car tyres. Typically, the radial tyre offers more landings per tread and lighter weight than a bias tyre; though sometimes at the expense of retread lives.
Radial aircraft tyres differ to bias aircraft tyres in that the plies all run radially from bead to bead at approximately 90° to the centre-line of the tyre. Angled belt plies are laid between the tread and the top casing ply, resulting in a flatter tread and adding strength to the tyre.
Bias ply tyre :
A bias-ply tyre has the fabric bias oriented with and across the direction of rotation and the sidewall. Since fabric can stretch on the bias, the tyre is flexible and can absorb loads. Tyre strength is obtained by adding plies.
Rolling resistance :=>
Rolling resistance is one of the forces that act to oppose the motion of a cyclist. It is caused mainly because of deformation of the tyre and can be understood by thinking about:
1. energy losses due to heat (hysteresis)
2. the forces pushing on the tyre.
Energy is lost as heat
As the tyre comes into contact with the road, it changes shape as it is compressed (pushed in a bit). This compression causes parts of the rubber tube and the casing of the tyre to heat up. It also causes the tread on the outside of the tyre to heat up as it comes into contact with the road. A tyre with knobbly tread will have a lot more rolling resistance than a smooth tyre because there will be more rubber being compressed and so there will be more heat.
The tyre is a bit like a spring or a rubber band. Some of the energy is stored as the tyre becomes compressed (squeezed in). As the tyre comes back off the road, there is not as much of this stored energy returned because some of it has gone towards making the tyre heat up. This loss of available energy due to heating is called hysteresis. This means there will be less energy available to make the bike go faster.
If you feel the temperature of your tyres when you have been biking fast, you will notice this heat. If your tyres are not pumped up hard, there will be even more heat created.
The force of rolling resistance does not change at higher speeds. However, because there is a lot more heat being produced at higher speeds, the cyclist uses more power (energy per second) to work against rolling resistance.
Forces on the front part of the tyre are greater
Forces on a tyre
Rolling resistance happens because the force pushing backwards against the tyre as it comes into contact with the road is bigger than the force pushing forwards as it leaves.
As the front part of the tyre touches the road, it takes a lot of force to squeeze in the tyre. This causes a backwards force on the wheel. As the tyre comes back off the road, there is a force pushing forwards on the wheel, but this forwards force is not as great. This is because of internal friction in the tyre.
If you could design a tyre that didn’t have internal friction and didn’t heat up, the force at the front section of the tyre contacting the road would be the same size as the force on the back section. This would mean zero rolling resistance, assuming there was no energy loss due to compression of the road surface.
Some things that affect rolling resistance
Rolling resistance depends on the mass of the cyclist and the bike, cornering, the design of your tyres, tyre pressure and road surface.
Mass – more mass means more downwards force due to gravity onto the road. This results in more tyre compression so rolling resistance increases. Carrying things like extra water bottles increases your rolling resistance.
Cornering – going through corners causes track cyclists to slow down, partly because cornering results in a greater downwards force into the track, which increases rolling resistance. (Cornering also increases rolling resistance because the rubber is twisting sideways on the road a bit, and this twisting produces more friction and heat.)
Design of tyres – choosing materials and construction that don’t heat up as much will result in less rolling resistance. One way to do this is to make your tubes out of specialised latex rubber. Racing tyres are very smooth, narrow and pumped up hard. The casing is also designed to minimise heat loss as it deforms. With as little of the tyre being compressed in as possible, there will not be as much of this heating effect, so there will be more energy available for more speed. There are many options for cyclists to consider.
Road or track surface – wooden cycle tracks contribute to a very low rolling resistance. Roughsealed roads have more rolling resistance. Grass and soft dirt surfaces are much greater. If the surface can be deformed, this increases rolling resistance markedly.
Choosing tyre materials and construction that don’t heat up as much will result in less rolling resistance.
Calculating rolling resistance
This equation is used to calculate the force of rolling resistance from each tyre:
FRR = CRR x weight
FRR is the rolling resistance force.
CRR is the coefficient of rolling resistance (a number used to rate each tyre at a given pressure),
weight is the force due to gravity being exerted on each tyre (= mass (kilograms) x 9.8).
This equation shows that speed does not affect the force due to rolling resistance. The type of tyre and the mass of the bike plus rider are the only two variables.
Tyre pressure =>
An aircraft tire or tyre is designed to withstand extremely heavy loads for short durations.The number of tires required for aircraft increases with the weight of the aircraft, as the weight of the airplane needs to be distributed more evenly. Aircraft tire tread patterns are designed to facilitate stability in high crosswind conditions, to channel water away to prevent hydroplaning, and for braking effect.
Aircraft tires also include fusible plugs (which are assembled on the inside of the wheels), designed to melt at a certain temperature. Tires often overheat if maximum braking is applied during an aborted takeoff or an emergency landing. The fuses provide a safer failure mode that prevents tire explosions by deflating in a controlled manner, thus minimizing damage to aircraft and objects in the surrounding environment.
Inflation :
Each of the twelve Boeing 777-300ER main tires is inflated to 220 psi (15 bar; 1,500 kPa), weighs 120 kg (260 lb), has a diameter of 134 cm (53 in) and is changed every 300 cycles while the brakes are changed every 2000 cycles.
Aircraft tires generally operate at high pressures, Inflation up to 200 psi (14 bar; 1,400 kPa) for airliners, and even higher for business jets.
Tests of airliner aircraft tires have shown that they are able to sustain pressures of maximum 800 psi (55 bar; 5,500 kPa) before bursting.
Aircraft tires are usually inflated with nitrogen to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight.
Brake forces and landing=>
Bringing at aircraft down to the runway from 37,000 feet is only part of the challenge. It’s not over until the aircraft is safely parked at its gate. In order to do this, pilots have a number of systems available to slow the aircraft down, even in a blizzard on a snowcovered runway.
The 787 braking system:
Stopping a 200-tonne aircraft landing at 180 mph requires a lot of braking force. To do this, the 787 has one brake unit on each of the eight wheels on the main gear assembly.
On other aircraft types, the brake units are powered by the hydraulics system. An electrical signal is sent from the flight deck to hydraulic actuators near the main landing gear. Here, hydraulic fluid at 3,000 pound per square inch is used to force the brake unit against the wheel, thus slowing it down.
That’s the case on the 787 Dreamliner. Designers did away with the use of the hydraulic system and all its associated architecture and instead used electricity to power the brakes. When the pilots press on the brake pedals, an electrical signal is sent to the brake unit on the wheel. Here, electrically powered actuators are used to press the carbon brake disc against the wheel, slowing it down.
Electric brakes
The brake system on the 787 Dreamliner is controlled by the pilots pressing the tops of the rudder pedals under their feet, demanding the rate of braking which they require. This sends an electronic signal to the Left and Right Brake System Control Units (BSCUs).
These then send signals to the four Electronic Brake Actuator Controllers (EBAC) which control the rate of braking on the wheels. Each wheel has four Electric Brake Actuators (EBA), a kind of piston which presses against the carbon brake discs.
The brake disks themselves are made up of two parts. Firstly, there are the rotors. These are connected to the wheel by drive tabs (in the video below they are the black rectangles on the rotor disks). As these drive tabs are in contact with the inside of the wheel, they spin at the same speed. Depending on the brake manufacturer, there are either four or five of these rotors on each brake assembly.
The second part of the disks are the stators. These sit around each rotor and are fixed in place and thus don’t move. As the wheel turns, the rotors spin round inside the stators.
When the brakes are applied, the four EBAs apply pressure to the first stator. This in turn squeezes the stationary stators up against the spinning rotors and it’s this friction which slows the wheel down.
Anti-skid protection
When landing on slippery runways, there’s a chance that the wheels may start to skid as the brakes are applied. To stop this from happening and to maintain maximum effective braking, each wheel has anti-skid protection.
Using a variety of sources to determine the aircraft speed, the brake units know how fast the wheels should be spinning. If that speed drops significantly, it’s because the current brake pressure on that wheel is too great and the wheel is just skidding over the surface.
In this situation, the anti-skid system automatically reduces the braking on that wheel to a point where the skid stops before reapplying the pressure. All this is done in a fraction of a second.
Autobrake
Pressing on the brakes is pretty straight forward when taxiing in a straight line at low speed. However, when we’re landing in strong winds, it can be a little tricky. We need to use our feet on the rudder pedals to line the nose of the aircraft up with the runway centerline at the last moment. Then, whilst holding that position, slide our feet up to press the toe brakes. Really not very easy when moving at 160 mph.
To help us get the braking underway as soon as we touch down, we have the autobrake system.This provides automatic braking at a preselected rate as soon as the aircraft senses that it is on the ground. It also provides full braking pressure in the case of a rejected takeoff if the speed is above 85 knots (98 mph).
Bottom line
Bringing an aircraft to a safe stop is the most important part of a flight. In order to do this, pilots have a number of facilities available to them.
The brakes bear the brunt of the hard work with the spoilers and reverse thrust lending a helping hand to ensure maximum efficiency. The autobrake system helps keep the deceleration nice and smooth whilst the anti-skid system reduces the distances needed to stop by modulating the brakes on individual wheels and stopping them from skidding.
Aircraft can also depart with part of the braking system not working. By carrying out a performance calculation before every takeoff and landing, we ensure that the aircraft will stop safely in the given conditions, even at maximum takeoff weight.
Q.6 With necessary assumptions, calculate the force and power required to push/pull an aircraft by a towing vehicle.
Ans=>
Let us Assume:
Weight of the Aircraft (Boeing 747-8) = 447,700kg
Rolling Resistance Coefficient of an aircraft tire = 0.004
Wight of the Tugs Tractor = 50000kg
Rolling Resistance Coefficient of Towing Vehicle = 0.0035
Then,
Rolling Resistance Force of Tugs Tractor =FRR = CRR x weight = .0035*50,000*9.81 =1,716.75 N
Rolling Resistance Force of aircraft =FRR = CRR x weight =.004*50,000*9.81 =17,567.748 N
Total Rolling Resistance Force = Rolling Resistance Force of aircraft + Tugs Tractor = 17.567+ 1.71675
Total Rolling Resistance Force = 19.28 KN
The Aerodynamic Drag is given by,
rho= Density of Air Medium
A = Frontal Area Of the Vehicle which strike the Air
V = Velocity with the vehicle moves
Cd= Coefficient of Dragwhich varies different shapes of the frontal area.
Calculation:
Let us assume
The Velocity of the Aircraft while Towing = 25 KMPH = 6.944 m/s
Density of Air medium = 1.25 kg/m3
The Frontal area of the Aircraft = 20 m2
The Frontal area of the Aircraft = 1.8 m2
The Coefficient of Drag of the Aircraft = 0.025
The Coefficient of Drag of the Tugs tractor = 1.15
Air drag force = 0.5*rho*A*V^2*Cd
The Air Drag Force of the Aircraft = .5*1.25*20*(6.944^2)*.025 = 15.07 N
The Air Drag Force of the Tugs Tractor = .5*1.25*1.8*(6.944^2)*1.15 = 62.38 N
Total Aerodynamic Drag Force = Air Drag Force of the Aircraft + Air Drag Force of the Tugs Tractor = 15.07 N + 62.38 N
Total Aerodynamic Drag Force = 77.45 N
Therefore the total force that the motor needs to overcome = Total Rolling Resistance Force + Total Aerodynamic Drag Force = 19.28 + .07745 (KN) = 19.362 KN
Thus Total Force that the Motor needs to overcome in order to push/pull the Aircraft = 19.362 KN
The Power Required-
The power required by the motor is given by the velocity with which the towing operation takes place.
The average speed of push/pull = 25 kmph = 6.9444 m/s
Power required by the motor = Total Force*Velocity = 19.362*6.9444
Power Required by The Motor = 134 KW
Q.7 Design an electric powertrain with type of motor, it’s power rating, and energy requirement to fulfill aircraft towing application. Estimate the duty cycle range to control the aircraft speed from zero to highest. Make all required assumptions. Prepare a table of assumed parameters. Draw a block diagram of powertrain.
Ans=>
The parameters assumed for designing this vehicle :
1. Weight of the Aircraft =447,700 kg
2. Weight of the Towing Tractor =50,000 kg
3. Rolling Resistance Coefficient of Aircraft = 0.004
4. Rolling Resistance Coefficient of Towing Tractor = 0.0035
5. The velocity of the Aircraft while Towing =6.944 m/s
6. Density of Air medium(rho) =1.25 kg/m^3
7. The Frontal area of the Aircraft =20 m^2
8. The Coefficient of Drag of the Aircraft =0.025
9. Towing Tractor Gear ratio(G- for high torque output) = 11
10. Towing Tractor tyre radus(r) =0.5 m
11. Operational time of the Towing for one cycle =.25 Hour(15min)
12. Power converters used Bidirectional DC-DC Boost Converter
As we have The Total Force that the Motor needs to overcome in order to push/pull the Aircraft = 19.362 KN
We have , F(Tractive)=T*(G/r)
Thus T = F(Tractive)*(r/G)
= 19362 * (.5/11)
= 880.090 Nm
So, Required power(P) = F * V
= 19.362* 6.944
=134 KW
Required Energy(E) for towing application based on the assumed time, that is E = P * t
= 134 (kw)* (.25hr)
= 33.5 KWh
Therefore the battery must be able to store the energy 33.5 KWH and should deliver the energy throughout the run time in order for the motor to produce the 880.09 Nm of torque . Thus the storage of energy in batteries with high performance Ultracapacitors are selected to fulfill the required power deliver.
Motor Selection:
Here we have selected a Permanent-Magnet Synchronous Motor (PMSM) type that has a power rating of 134 kw and with the gear ratio and the transmission it should be able to deliver 880.09 Nm of torque instantaneously.
Motor Parameter:
Type = PMSM
Model No. = APEV80- 12(16)
Phase = 3
Application = Electric bus, Truck , passenger car
AC Voltage = 200-750 VDC
Pole = 12
Direct Current Voltage (VDC) = 540
Rated current (A) = 255
Peak Current (A) = 650
Rated Power (kW) = 150
Peak Power (kW) = 220
Rated Speed (RPM) = 1,650
Peak Speed (RPM) = 3,300
Rated Torque (N.m) = 868
Peak Torque (N.m) = 3,000
BEMF (VAC)/rpm = 660/ 2401
rms
Insulation Grade = H
Protection Class = IP67
Cooling = Water
Weight (Kg) = 260
Efficiency of motor = 90 % (Assumed Parameter)
Now Duty Cycle Calculation :
The motor output power is the input power of the tugs tractor so to obtain maximum speed, the duty cycle needed is calculated as,
Duty Cycle = Output Power/Input Power
= (134/166.666) .....(Motor Input Power = Rated Motor Power/Motor Efficiency
= 150 / .9 = 166.666 kw )
.......(Power required for aircraft towing = 134 kw)
= 0.80399
=80.399 %
The duty cycle will be 80.399 %
The duty cycle range to control the aircraft speed from zero to highest is from 0 to 80.399 % .
Block Diagram of Powertrain for Towing Vehicle-
This is how we selected motor and its power rating for towing application of aeroplane.
Then the power converters are used to upscale the battery armature voltage to through desired high voltage value so that the motor may spin at full power and required torque can be achieved using a Bidirectional DC-DC Converter.
Finally the speed control of the vehicle is done with switching techniques where the Duty Cycle adjustment can change the motor speed from the minimum to maximum.